Computing systems are capable of allowing users make edits to a table in a document, such as causing cells in the table to merge. In some existing table editors, such as HTML, cells are not strictly “merged.” Instead a cell is allowed to expand to take up more space either vertically or horizontally, and the “merged” cells are simply hidden. In this case, the merged cell and the expanding cell are not associated with each other, which can lead to complications in a controller that represents the table. Moreover, no limits are placed on the amount that the expanding cell can expand, which further complicates the model. In other table editors, such as OOXML, cells expand horizontally and cover up cells vertically. However, OOXML requires that the covering cell is explicitly marked as a covering cell, and that the covered cell is also explicitly marked as a covered cell. This direct dependency between the two covering cell and the covered cell in OOXML can cause problems in real time collaborative models, because a change to any cell in the table can affect any other cell.